At the present time, industry is using many robot-type welding apparatuses that perform various kinds of welding, and which involve the problem of sequential pressure welding of various thicknesses of metal. The sequential welding of various thicknesses of metals requires a changing of pressures in such welding apparatuses as they sequentially weld various thicknesses of metal. In order to provide the changing working pressures required, for welding such various thicknesses of metal, the welding industry has heretofore employed large selector air valves, with large spring operated regulators, and with each regulator supplying a different set pressure to the large selector air valves. These valves supply multiple pressures for the welds. The disadvantages of the use of such a large spring operated regulator and selector air valve package is that they are expensive, space consuming and inefficient because of the inherent spring rate of the large springs used in such regulators in combination with large selector power valves.